Mammatus clouds form in North Texas on Sunday night. Here's how they are formed.

Many FOX 4 viewers sent in their photos and video of interesting cloud formations across North Texas on Sunday. FOX 4 meteorologist Evan Andrews talks a bit about mammatus clouds and how they are formed. #txwx #weather

[@SparkGabs]

The clouds have been looking like this in Lubbock, TX!! I have so many pics

[@robertballesteros2275]

I saw it while in US Hwy 75 at Royal Lane started after the storm and they grew better and uglier after 30 min. I was so scared at its monster appearance!

[@cinamy151]

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